From Genome to Life:

BRANDINA Irina

Moscow State University, Molecular Biology, Leninskije Gory, Moscow 119899, Russia

title: The search of protein factors of RNA import into yeast mitochondria using yeast two- and three-hybrids systems.

The cytoplasmic tRNALys(CUU) is the single yeast tRNA species to be trafficked from the cytoplasm into the mitochondrial compartment of the cell. To study mechanisms of this targeting it was worked out in vitro system. It requires the presence of ATP-generation system and soluble cellular proteins in the reaction mixture. At least two protein factors are necessary to direct the import in vitro. The first one is precursor of the mitochondrial lysyl-tRNA synthetase (preMSK), the second is cytoplasmic lysyl-tRNA synthetase. However, cooperation of the two synthetase is not sufficient to direct tRNA import, suggesting the need of additional factor(s). To find potential factor(s) of import we used yeast two-hybrid and three-hybrid systems. The two-hybrid system allowed us to identify proteins that interact with preMSK. The three-hybrid system was used to identify proteins which were specifically binding with importing tRNALys. During comparing results obtained by both methods, we found some proteins, which were identified in both systems. Now we are planning to test them as factors of tRNA import into mitochondria using different in vivo and in vitro test.